Image file formats

There are three main types of digital image file formats, classified by their position in the production process:

  • Camera capture formats, such as Camera Raw (non-lossy) or JPG (lossy)
  • Editing formats, like Photoshop’s  .psd or Gimp’s  .xcf
    • Also called “original” or “native” formats
    • Saving in  .psd or .xcf retains layers and other work underway
    • Can’t be opened by web browsers or any other application
  • Interchangeable formats (can be opened by any image editor)
    • Formats for web  –  .gif,  .jpg,   .png, .heic,  .webp   (All are compressible, or “lossy;”  .heic and .webp are newest and most flexible)
    • Formats for printing —  .pdf and  .tiff  (.tiff is not for web, but .pdfs can be read by web browsers. )

This is a simplified overview of the most significant formats, attributes and  uses.

Name Channels Mode Color depth Suffix Pro / Con  Typical Use
Raw     (camera capture / input)    3  Raw 
  12 or 14 bits  per channel (4096-16384 shades) Depends on camera type. EX: .crw (Canon) Lossless
Retains full gamut before formatting		 Storage in camera NOT FOR WEB
GIMP Gnu Image Manipulation Program  4 (any) Working format (original format for GIMP)
 .xcf Lossless NOT FOR WEB 
Adobe Photoshop  4 (any) Working format (original format for Adobe Photoshop)
 .psd Lossless
No  compression   		 NOT FOR WEB 
 Adobe Portable Document Format  N/A  File exchange. format  .pdf   Lossless, can be compressed OK for WEB Flat text, graphics,  interactive elements,  rich media
Graphic
Image
Format		 1  Indexed, greyscale  8 bit, only 256 total colors but pallets vary
 .gif Lossless,  good for  transparency, animation FOR WEB – Simple colors, maps &  cartoons 
Joint
Photographic
Experts
Group 
 3 RGB 16 million colors
(no alpha channel  transparency)		 .jpg .jpeg
 Good compression  FOR WEB – Complex photos.  Introduced 1992 
Scalable Vector Graphics  3 RGB 16 million colors; not for photos
 .svg
 Scalable without aliasing / Not bitmapped FOR WEB  
Portable
Network
Graphics		 4 RGB 16 million colors plus alpha channel (transparencies).  .png Better compression than jpg,  Best for https   FOR WEB Introduced 1998
High Efficiency Image Container  RGB  16 million colors, for images and  multimedia, audio & video .heic  Default for Apple devices  FOR WEB Introduced 2015 
Webp RGB  16 million colors .webp lossy good  compression,  alpha channel FOR WEB (introduced 2010 by Google) 
Tag Image File Format  Usually CMYK Billions of  possible colors  .tiff, also 
.pict  / old Apple
format 		 Some  compression FOR PRINTING, ARCHIVING  
Flexible image transport system  4 (any) Scientific and archival format  .fts, .fits Non-lossy; backwards compatible (to 1981). Good photometric notations Working format for FITS Liberator
NOT FOR WEB 

 

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